From b59bf78e16e6672a84460a94ba5e6249a4c22ca4 Mon Sep 17 00:00:00 2001
From: Raam Dev <raam@websharks-inc.com>
Date: Mon, 27 Jun 2016 21:03:54 -0400
Subject: [PATCH] Fix upgrade bug w/ COMET_CACHE_ALLOW_CLIENT_SIDE_CACHE
 undefined warning

See websharks/comet-cache#789
---
 src/includes/classes/VsUpgrades.php        | 7 ++++++-
 src/includes/traits/Ac/ClientSideUtils.php | 4 ++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/includes/classes/VsUpgrades.php b/src/includes/classes/VsUpgrades.php
index 91b8a0f4..70b8fc06 100644
--- a/src/includes/classes/VsUpgrades.php
+++ b/src/includes/classes/VsUpgrades.php
@@ -42,6 +42,7 @@ protected function runHandlers()
         $this->fromLte151114();
         $this->fromZenCache();
         $this->fromLte160227();
+        $this->fromLte160521();
     }
 
     /**
@@ -227,14 +228,18 @@ protected function fromLte160227()
     /**
      * Before we renamed the Auto-Cache Engine requirements check notice to `auto_cache_engine_minimum_requirements`,
      * and before we renamed the `allow_browser_cache` option to `allow_client_side_cache`,
-     * and before we added the `htaccess_access_control_allow_origin` option.
+     * and before we added the `htaccess_access_control_allow_origin` option,
+     * and before we renamed COMET_CACHE_ALLOW_BROWSER_CACHE to COMET_CACHE_ALLOW_CLIENT_SIDE_CACHE.
      *
      * @since 16xxxx
      */
     protected function fromLte160521()
     {
         if (version_compare($this->prev_version, '160521', '<=')) {
+            global $is_apache; // WP global for web server checks below.
+
             $this->plugin->dismissMainNotice('allow_url_fopen_disabled');
+            $this->plugin->removeAdvancedCache();
 
             if (is_array($existing_options = get_site_option(GLOBAL_NS.'_options'))) {
                 if (isset($existing_options['allow_browser_cache'])) {
diff --git a/src/includes/traits/Ac/ClientSideUtils.php b/src/includes/traits/Ac/ClientSideUtils.php
index 83d55625..09242694 100644
--- a/src/includes/traits/Ac/ClientSideUtils.php
+++ b/src/includes/traits/Ac/ClientSideUtils.php
@@ -12,6 +12,10 @@ trait ClientSideUtils
      */
     public function maybeStopBrowserCaching()
     {
+        if (!defined('COMET_CACHE_ALLOW_CLIENT_SIDE_CACHE')) {
+            return $this->sendNoCacheHeaders(); // Upgrading from <= v160521, before we renamed this constant. Return default.
+        }
+
         switch ((bool) COMET_CACHE_ALLOW_CLIENT_SIDE_CACHE) {
 
             case true: // If global config allows, check exclusions.